Functions of Mucin-Type O-Glycans in the Nervous System

Glycans play a role in neural circuit formation and higher brain functions such as memory and learning in nervous system. Mucin-type O-glycans are present at high levels on mucins and T-cell immunoglobulin and mucin domains (TIM). Mucins are secreted from epithelial cells present in digestive organs. TIM possesses a T-cell immunoglobulin and mucin domain, and functions in the immune system. In addition, several mucin-type O-glycans are highly expressed in cancer cells and are thus used as a diagnostic marker. We previously found that T antigen, a mucin-type O-glycan, is highly expressed in the nervous system of Drosophila; however, the functions of mucin-type O-glycans in the nervous system remained largely unknown. In this review, we describe the functions of mucin-type O-glycans in the nervous systems of mammals and invertebrates, focusing mainly on the role of T antigens in nervous system of Drosophila, which we have recently reported.